Process of rendering wool unshrinkable



Patented May 16, 1950 mnnma'woor. namxanu:

Rudolf Bloch and Ladislaw V..Farkal, Jerusalem, Kurt Goldschmid, Tel Aviv, and Mendel Lewin, Isaac Schnerb, and Paul Goldschmidt, Jerusalem, Palestine; Hanna Farkas executrix of said Ladislaw V. Farkas, deceased No Drawing. Application July 17, 1946, Serial No. 684,254. In Palestine August 13, 1945 PROCESS OF it UNS 1 This invention relates to processes of renderin: wool unshrinkable.

.It is known that wool can be rendered unshrinkable by treatment with elementary chlorine or bromine either in the gaseous state or dissolved in water or organic solvents, e. g. alcohol or carbon tetrachloride, or with anacidulated aqueous solution of hypochlorite. In these known processes the action of the halogen on the wool fibre is so vigorous and quick-in fact it is accomplished in a few seconds only-that it cannot properly be controlled. Consequently, the effect of this treatment is not uniform: while a part of the batch has just reached the desired degree of unshrinkability, another part thereof has already got more than its proper share of halogen and sufiered damage by the latter. The feel of the wool so treated is unsatisfactory, and the increase of its color reception properties which, as is known, is brought about by the halogen, is not uniform which leads to the formation of stainswhen the wool is subsequently dyed. On theother hand it is known that the color reception properties of wool can be improved by treatment with a highly dilute aqueous solution of alkali bromate in the presence of hydrochloric acid and that such treatment does not aifect the felting and shrinking properties of the wool. I

It has now been found that'wool can be made unshrinkable by a well-controllable treatment with an aqueous solution of alkali bromate and wool. Speakman (Journal of Textile Inst., vol.

22, No. 'I, 1941) found that the amount of acid .so absorbed is equivalentto about 800 cc. of N/ acid (1. e. about 0.08 gram-equivalent) per 100 grams of air-dry wool. The character of this absorption is not yet fully recognized. On the one hand the acid disappears for allvintents and purposes from the solution and cannot be found back by titration, on the other hand it can be eluted from the wool by intensive washing with much water. It may, therefore, be assumed that it is bound in salt bond to protein and that the 5 Claims. (CI. 2876) bond is liable to be severed by hydrolysis (see also Speakman, l. c.). Where the solution contains several acid anions, e. g. in the case of a mixture '0! hydrochloric acid and bromate, the total amount of anion absorbed by the wool substantially corresponds to the total amount of absorbed hydrogen ion, but the anions are absorbed in a proportion relative to one another substantially equal to their original proportion in the said solution. By elution they are again liberated 30m the wool substantially in the same propor- The shrinkprooflng eifect obtained by the treatment of wool with hydrochloric acid and bromate according to this invention is due to bromate present in the treating liquor over and above the absorbed quantity. Again the exact nature of the action of the bromate on the wool is-not yet recognized but it can be stated with certainty that the effective part of the bromate is irretrievably lost, in contrast to the absorbed portion of bromate which, upon being eluted from the wool, is recovered as bromate.

Accordingly, this invention consists in a process of shrinkproofing wool by treatment with an aqueous liquor containing free hydrochloric acid and water-soluble bromate over and above the amounts of acid and bromate ion liable to be absorbed by the wool, and the treatment is so controlled that an amount of bromate ion of from 6.4 to 16 grams per kilogram of air-dry wool is thereby consumed.

The exact amount of bromate that any particular specimen of wool requires for shrinkrti-otgfing has to be ascertained by preliminary After the treatment with bromate the wool is after-treated. with a .view. to removing any bromate or free halogen left, e. g. by rinsing, washing. with dilute ammonia, soaking with an alkali bisulfite solution, and againv rinsing.

The hydrochloric acid maybe added to the liquor as such or be generated therein from chloride and another acid or an acid salt, e. g. sulfuric acid or a bisulfate.

. It is advisable to add to the liquor acid-resisting wetting agents, asknown per se, e. g. alkali lauryl sulfate or oleyl sulfate, and protective colloids, e. g. glue, gum or the like.

The shrinkprooflng treatment according to this invention may be combined with a milling treatment. In this case the cloth is first immersed in a liquor containing the shrinkproofing agents, and milled therein till the desired degree of thickening has been obtained, then the milling is interrupted and the cloth is left for some time in the liquor without further mechanical agitation, and thereby stabilized in the state of thickening produced by the milling. For the milling 3 operatiomtheliquormayeontainalreadythefull amount of acid and bromate required for shrinkprooflng, or the acid and/or bromate may first be present inless than the full quantity needed for shrinkproonng and the balance be added when the milling is interrupted.

The invention is illustrated by the following examples.

Example 1 is of the order of 29 grams of HCl, and that of bromate ion of the order of 7.7 grams. The rate of disappearance of bromate and acid during the treatment is followed by titration of the acid and bromate contained in samples taken from the liquor at short intervals. After 40 to 60 minutes, an amount of bromate ion of about 8 grams has disappeared over and above the 7.7 grams of absorbed bromate ion mentioned above. When this is the case, the wool is removed from the vat, rinsed with water and introduced into a bath of about litres of water containing 1 gram of ammonia per litre, left therein for about minutes, rinsed and brought into a second bath of about 25 litres of water which contains 1 gram of sodium bisulflte per litre and is kept at 50 C. After about 45 minutes the wool is again rinsed, centrifuged and dried.

Example 2 1 kg. of wool is treated for about one hour in 23 litres of a liquor which is kept at 25 C. and contains per litre: 3.6 grams of KBrO: (corresponding to about 2.8 grams of bromate ion).-

13.5 grams of NaCl (corresponding to about 8.4 grams of H01), 27 grams of potassium bisulfate and 0.2 gram of a wetting agent. For the rest, the treatment is carried out as described in Example 1.

Example 3 The treatment and composition of the liquor are the same as described in Example 1, except that the temperature of the liquor is C. and the amount of HCl 3 grams. Duration of the treatment: 60 to 80 minutes.

Example 4 Composition of the liquor: 23 litres containing per litre: 5.25 grams of-potassium bromate (corresponding to 4 grams of bromate ion), 8 grams of HCl, 5 grams of glue and 0.2 gram of wetting agent. Temperature 12 0., duration minutes, otherwise as described in Example 1.

Example 5 ample 1.

trample 6 1kg.ofwoolistreatedat60C.in50litreso1 a liquor which contains per litre: 0.5 gram of bromate ion (in the form of potassium bromate) 2.25 grams of hydrogen chloride and 0.2 gram of sodium lauryl sulfate. After about minutes, the consumption of bromate ion amounts to about 9.5 grams. The wool is then removed from the liquor and further treated as described in Example 1. Example 7 1 kg. of wool is treated at C. in 60 litres of a liquor which contains per litre: 0.4 gram of bromate ion (in the form of potassium bromate) 1.85 grams of hydrogen chloride and 0.2 gram of sodium lauryl sulfate. After about minutes, the consumption of bromate ion amounts to 8.6 grams. The wool is then removed from the liquor and further treated as described in Example 1.

Example 8 1 kg. of wool is immersed in a fulling mill in 23 litres of a liquor containing per litre: 6 grams of hydrogen chloride (calculated as pure HCl) and 0.8 gram of bromate ion (in the form of potassium bromate) and milled at 25 C. till the desired degree of thickening has been obtained. Then the milling is interrupted, a further 0.8 gram of bromate ion (as potassium bromate) per litre is added and the cloth is left in the liquor without mechanical agitation for about 35 minutes, and further treated as described in Exam ple 1.

We claim:

'1. The process of shrinlrprooflng wool, which comprises immersing the wool in an aqueous liquor containing hydrochloric acid and water-soluble bromate in excess over the amount of acid and bromate absorbable in the wool, which absorbable amount corresponds to about 0.08 gramequivalents per grams of air-dry wool, the excess of bromate (expressed as bromate ion) being not less than 1.5%, and that of hydrochloric acid (expressed as HCl) being comprised between 6 and 20%, both calculated on the weight of airdry wool; leaving the wool in the liquor until bromate ion. has disappeared therefrom in an amount of about 0.65 to 1.6 grams per 100 grams of air-dry wool; withdrawing the wool from the liquor and removing excess treating liquor from the wool.

2. A process as claimed in claim 1 wherein a wetting agent is added to the treating liquor.

3. A process as claimed in claim 1 wherein a protective colloid is added to the treatin liquor.

4. The method of treating woollen cloth by a combined milling and shrinkprooflng process comprising immersing the cloth in a fulling mill in an aqueous liquor containing hydrochloric acid and water-soluble bromate in excess over the amount of acid and bromate absorbable in the wool, which absorbable amount corresponds to about 0.08 gram-equivalents per 100 grams of air-dry wool, the excess of bromate (expressed as bromate ion) being not less than 1.5% and that of hydrochloric acid (expressed as 1101) being comprised between 6 and 20%, both calculated on the weight of airdry wool; milling the cloth until the desired degree of thickening has been obtained, interrupting the milling and further leaving the cloth in the liquor until bromate ion has disappeared therefrom in an amount of about 0.65 to 1.6 grams per 100 grams of air-dry wool; withdrawing the cloth from the liquor and removing excess treating liquor from the cloth.

5. The method or treating woollen cloth by a combined milling and shrinkprooflng process comprising immersing the cloth in a iulling mill in an aqueous liquor containing hydrochloric acid and water-soluble bromate in at least the amount thereol absorbable in the wool, which absorbable amount corresponds to about 0.08 gram-equivalents per 100 grams of air-dry wool, and at least hydrochloric acid in excess over said absorbable amount, the excess amount of the acid (expressed as HCl) being comprised between 6 and 20% by weight of air-dry wool; milling the cloth until the desired degree of thickening has been obtained, interrupting the milling, adding to the liquor so much further water-soluble bromate that the liquor contains a total excess of bromate ion, over and above the aforesaid absorbable amount, of not less than 1.5% by weight of air-dry wool; leaving the wool in the liquor until bromate ion has disappeared therefrom in an amount of about 0.85 to 1.8 grams per 100 grams or airdry wool; withdrawing the cloth from the liquor, and removing excess treating liquor from the cloth.

-' R. BLOCH.

L. V. FARKAS. K. GOLDBCHMID. M. LEWIN. ISAAC BCHNERB. PAUL GOLDSCHMDT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS Switzerland Feb. 17, 1930 

1. THE PROCESS OF SHRINKPROOFING WOOL, WHICH COMPRISES IMMERSING THE WOOL IN AN AQUEOUS LIQUOR CONTAINING HYDROCHLORIC ACID AND WATER-SOLUBLE BROMATE IN EXCESS OVER THE AMOUNT OF ACID AND BROMATE ABSORBABLE IN THE WOOL, WHICH ABSORBABLE AMOUNT CORRESPONDS TO ABOUT. 0.08 GRAMEQUIVALENTS PER 100 GRAMS OF AIR-DRY WOOL, THE EXCESS OF BROMATE (EXPRESSED AS BROMATE ION) BEING NOT LESS THAN 1.5%, AND THAT OF HYDROCHLORIC ACID (EXPRESSED AS HC1) BEING COMPRISED BETWEEN 6 AND 20%, BOTH CALCULATED ON THE WEIGHT OF AIRDRY WOOL; LEAVING THE WOOL IN THE LIQUOR UNTIL BROMATE ION HAS DISAPPEARED THEREFROM IN AN AMOUNT OF ABOUT 0.65 TO 1.6 GRAMS PER 100 GRAMS OF AIR-DRY WOOL; WITHDRAWING THE WOOL FROM THE LIQUOR AND REMOVING EXCESS TREATING LIQUOR FROM THE WOOL. 